Method for the introduction of volatile additives into a melt

ABSTRACT

INTRODUCTION OF VAPORIZABLE ADDITIVES, SUCH AS MAGNESIUM, INTO AN IRON MELT IN WHICH THE VAPORAZATION IS INITIATED BY A TILTING MOVEMENT OF A TREATMENT VESSEL. THE VAPORIZABLE MATERIAL IS CONTAINED IN A SEPARATE CONPARTMENT WHICH CAN BE EXTERNALLY CHARGED AND WHICH, IN ONE POSITION OF THE VESSEL SEGREGATES THE ADDITIVE FROM HTE MELT, BUT ON TILTING THE VESSEL, PERMITS COMMUNICATION WITH THE MELT THROUGH OPENINGS LOCATED A DIFFERENT LEVELS. THE VAPOR BUBBLES FORMED ASCEND THROUGH THE MELT WITH SUCH A SIZE AND IN SUCH A NUMBER THAT AT LEAST A PORTION OF THE BUBBLES ESCAPE FROM THE SURFACE OF THE MELT. THE VAPOR BUBBLES HAVE A GREAT SURFACE AREA TO PROVIDE, FOR EXAMPLE WITH MAGNESIUM, A YIELD OF AT LEAST 30% AND PREFERABLY MORE THAN 40% OF THE ADDITIVE IN THE MELT WHILE THE VELOCITY OF THE ASCENDING VAPOR BUBBLES IS SUCH AS TO PRODUCE A FLUSHING ACTION ON THE MELT RESULTING IN A REDUCTION OF THE REACTION PRODUCTS AND RESIDUAL UNDESIRABLE IMPURITIES IN THE MELT.

A. ALT

May 30, 1972 METHOD FOR THE INTRODUCTION OF VOLATILE ADDITIVES INTO AMELT Filed Jan. 22, 1969 INVENTOR ///7a// 4Z6 f ATTORNEYS United StatesPatent ice 3,666,449. Patented May 30, 1972 US. Cl. 75-130 B 12 ClaimsABSTRACT OF THE DISCLOSURE Introduction of vaporizable additives, suchas magnesium, into an iron melt in which the vaporization is initiatedby a tilting movement of a treatment vessel. The vaporizable material iscontained in a separate compartment which can be externally charged andwhich, in one position of the vessel segregates the additive from themelt, but on tilting the vessel, permits communication with the meltthrough openings located at different levels. The vapor bubbles formedascend through the melt with such a size and in such a number that atleast a portion of the bubbles escape from the surface of the melt. Thevapor bubbles have a great surface area to provide, for example withmagnesium, a yield of at least 30% and preferably more than 40% of theadditive in the melt while the velocity of the ascending vapor bubblesis such as to produce a flushing action on the melt resulting in areduction of the reaction products and residual undesirable impuritiesin the melt.

BACKGROUND OF THE INVENTION The present invention relates to an improvedmethod for the introduction of volatile or vaporizable additives into amelt, especially magnesium, into an iron-carbon melt, in which thevaporization is initiated by a tilting movement of the treatment vesselwhereby the volatile additives are immersed beneath the surface of themelt, and further, wherein the speed of vaporization is retarded bymeans of a receiving compartment for the additives which are to bevaporized, such receiving compartment being equipped with openingsdirected into the interior of the treatment vessel and relates furtherto the use of the same for the production for various materials.

The introduction of magnesium into iron melts is the surest technicaland the most economical manner to produce iron-carbon cast materialswith spherical graphite. In so doing, magnesium, as well as also otherelements of the earth alkaline group and the group of the rare earths,causes, in known manner, a separation of the graphite in spherical formduring solidification and/or subsequent heat treatment, and thereforeresults in improved mechanical properties.

However, the introduction of magnesium is associated with knowndifiiculties. Its specific weight of 1.74 g./cm. is considerably lowerthan that of the iron melts. Above all magnesium, with a boiling pointof 1107 C. at a generally encountered temperature of the iron melt of1480" C., develops a vapor pressure of approximately 12 atmospheres.Therefore, in the majority of instances, magnesium is introduced in theform of key alloys or hardeners with a magnesium content of to 30% intothe melt which is to be treated, since the vapor pressure is reduced inaccordance with the dilution.

However, the use of key alloys or hardeners possesses the drawback thatother elements are introduced into the melt to a certain degree inundesirable quantities. Consequently, the possibility of using such keyalloys or hardeners is generally limited. The use of such materialsnecessitates starting with melts of low sulfur content. Melts of lowsulfur content can ordinarily only be realized in a basic meltingfurnace unit or in an acidic melting furnace unit while using asulfur-poor material charge or by using a special desulfurizingtechnique. Moreover, the use of key alloys or hardeners is associatedwith increased costs. Thus, the cost for the same quantity of addedmagnesium utilizing conventional key alloys or hardeners amounts toabout five to twenty times that of using pure magnesium.

Accordingly, a whole series of techniques have become known to the artwhich are concerned with the introduction of pure magnesium into theiron melts. Thus, at the present time, a small quantity of cast ironwith spherical graphite may be produced according to a technique inwhich pure magnesium is added under a pressure which corresponds to thevapor pressure at the given treatment temperature. Methods are alsoknown to the art wherein pure magnesium is continuously, added in solid,liquid, or gaseous condition, the speed of reaction being controlled bythe speed with which the material is added. It has also already beenproposed to reduce to an acceptable degree the vigor or intensity of thereaction of magnesium during continuous or one-time addition by mixingthe same with suitable inert materials in powdery-or pasty-likecondition, by imbuing porous materials with magnesium, by the use ofsuitable coatings, or by introducing the magnesium into a containerhaving predetermined openings limiting the contact with the melt.

In addition to the conventional methods of adding magnesium to the meltby pouring-over, immersion or introduction with a pipe or similardevice, it has also been proposed heretofore to bring about the additionor introduction in such a manner that the magnesium is placed into atiltable vessel within a specially provided pocket therefor. Afterfilling with iron the magnesium is brought below the surface of the bathby carrying out a tilting movement through about Additionally, atechnique has also become known according to which the device providedfor the reception of the magnesium is constructed in the form of acompartment which can be externally charged and which is equipped withan opening towards the inside, the size of which is decisive for theheat delivered by convection to the magnesium through the melt and,therefore, for the speed of vaporization. The drawback of this methodresides in the fact that the considerable quantity of vapor hinders thecontinuous flow of heatsupplying melt. Consequently, on the one hand,this causes an irregular reaction process which is associated withviolent eruptions and, on the other hand, the dimensioning of theopening towards the lower extreme is limited and thus renders impossiblea delay or retardation of the reaction to the desired degree.

According to another known method, the yield is considerably increaseddue to the arrangement of a number of small openings, whereby the meltdoes not enter into the chamber or compartment containing the magnesium,rather the heat required for vaporization is delivered by conductingheat through the walls of the chamber. However, with this technique, theflushing effect is practically lost.

SUMMARY OF THE INVENTION Therefore, it is a primary object of thisinvention to provide a method for the introduction of vaporizablematerials to an iron melt which is free from the foregoing 'and othersuch disadvantages.

It is a further object of this invention to provide techniques for theaddition of varoprizable materials, specifically magnesium, wherein thevapor bubbles of the vaporizing additives are permitted to ascendthrough the 3 melt with a size and speed that there occurs a ratherextensive absorption of the vapor by the melt and, additionally, thebubbles cause a flushing action which is efiective to separate thereaction products between the melt and the va or.

EX still further object of this invention is the provision of a methodfor the addition of other materials such as fluxing agents and carbon tothe melt simultaneously with the addition of the vaporizable materials.

The basic objects of the invention are to permit the vapor =bubblesformed by the additives to ascend through the melt with such a size andin such a number that at least a portion of the formed vapor bubblesescape from the surface of the bath with such a large velocity that theascending bubbles exert a flushing action upon the melt. This results ina reduction of the reaction products and residual undesirable mixturesor impurities in the melt. On the other hand, the size of the vaporbubbles is chosen to be such that there results a sufficiently greatreaction surface of the vapor bubbles ascending in the melt wherebythere is obtained a favorable yield of the additives introduced into themelt, for instance, a magnesium yield in iron-carbon melts at the usualtreatment temperature of at least 30% and preferably above 40%.

In other words, the invention method is characterized by the fact thatthe vapor bubbles of the vaporizing additives are permitted to ascendthrough the melt with such a size and in such a number that, on the onehand, there occurs as extensive as possible absorption or reception ofthe resulting vapor by the melt and, on the other hand, a favorableflushing action for separating reaction products between the melt andthe resulting vapor. During the introduction of the additives into themelt, the same can be simultaneously subjected to a circulatorymovement.

As indicated, the invention is also concerned with the provision of animproved tiltable treatment vessel for car rying out the aforesaidinventive process. This tiltable treatment vessel is manifested by thefact that it possesses at least one rigidly-mounted receivingcompartment for the additives which compartment can be charged from theoutside, that is externally of the vessel. This receiving compartment isarranged at least at 'a portion of the base surface of the interior ofthe ladle or vessel when the vessel is tilted to its treatment orvertically-extending position. Yet, the interior or inner chamber of thereceiving compartment does not communicate with the melt when the vesselis in its filling or horizontally-extending position. Further, thecompartment includes a number of openings directed towards the interiorof the treatment vessel, which openings are arranged and constructed insuch a fashion that the melt passes into the compartment from thetreatment vessel through at least some of the openings when the vesselis in its treatment position to vaporize the vaporizable additives witha certain speed and then passes back through at least some of theopenings from the compartment into the interior or inner chamber of thetreatment vessel.

According to the instant inventive concepts, the techniques hereof maybe used for treating cast iron or malleable cast iron melts which havebeen molten in an acidic process without prior desulfurization, withtechnically pure magnesium or alloys containing large quantities ofmagnesium. Further, these techniques may be used for the production ofcast iron with a carbon content of 2.5 to 3.8% carbon, as well as forthe production of gray cast iron and cast iron with vermicular graphite.I

By virtue of the instant invention, there is simultaneously attained,with an exceptional yield of, for instance, magnesium, such a flushingor agitation effect that the reaction products formed between the meltand the vapor, for instance, magnesium sulfide, are separated from themelt. In contrast, with known techniques wherein the melts are treatedwith magnesium, the use of melts having a higher starting sulfur contenthave been excluded due to the formation of undesired inclusions.Consequently, the known treatment of sulfur-rich iron melts, forinstance, cast iron or malleable cast iron melts from the acidic cupolafurnace cannot be undertaken without previous desulfurization andwithout harmful products of reaction remaining in the melt. Sulfur-richstarting melts treated according to the inventive method manifestthemselves, for instance, by a lower content of sulfur remaining in themelt.

As mentioned, it is advantageous, according to this invention, to equipthe receiving compartment or chamber with openings which permit themagnesium vapor bubbles to ascend with such a size or magnitude throughthe melt that the magnesium yield amounts to at least 30% andpreferably, more than 40%.

BRIEF DESCRIPTION OF THE DRAWING The invention will be betterunderstood, and objects other than those set forth above will becomeapparent, when consideration is given to the following detaileddescription thereof. Such description ma'kes reference to the annexeddrawing, wherein:

FIG. 1 schematically illustrates an exemplary embodiment of a tiltabletreatment vessel according to this invention in its filling orhorizontally extending position; and

FIG. 2 depicts the tiltable vessel shown in FIG. 1 in its treatment orvertically extending position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingand, more particularly, to FIG. 1, it will be seen that the treatmentvessell is lined with refractory material and is filled while in itshorizontally extending position with melt 2 to such an extent that thereceiving compartment or chamber 3, which can be charged from theoutside or externally, remains free, that is to say, does notcommunicate with the iron melt 2. After opening the stopper or plug 4,the receiving compartment or chamber 3 is charged with the vaporizableadditive 5 with the addition of possible further additives, as will beexplained hereinafter. By means of the stopper or closure 4, thecharging opening of the receiving chamber or compartment 3 is closed andby means of a suitable cover member 6, the charging opening of thevessel 1 is likewise closed. The cover 6 contains an opening of 10 to 50mm. diameter which is aligned with an opening in the tea can-likepouring spout of the vessel 1 when the cover 6 is in its closed positionto vent the vessel.

After closing the plug 4 and the cover member 6, the entire treatmentvessel 1 can be tilted by a remote controlled drive mechanism (notshown) into the treatmen or vertically extending position depicted inFIG. 2. In the vertically extending position of the treatment vessel 1,the receiving compartment 3 is located below the surface of the melt 2,and the melt passes via the openings 7 and 8 into the interior of thereceiving compart-ment 3 where it contacts the additive 5 causingvaporization of the same. The formed vapor escapes in accordance withthe lift through the discharge openings 8 arranged at the top of thereceiving compartment 3, while the melt 2 continuously flows through theinlet openings 7 arranged at the lower region of the receivingcompartment 3. Accordingly, the delivery of the heat in this mannerassists and supports the vaporization process which is associated with aconsiderable take-up of heat. By appropriately dimensioning thecross-section of the openings 7 and 8, it is possible to predeterminethe reaction velocity or speed of the pure magnesium 5 located in thereceiving compartment 3, without requiring undesired additivematerials.The walls of the compartment 3 are preferably formed of refractorymaterial, preferably clay graphite plates of 10 to 50 mm. thickness. Theopenings 7 are preferably of a diameter of 20 to 40 mm. and the openings8 are preferably of a diameter of to 30 mm. with the openings 8distributed over at least a third of the base surface of the vessel 1and the entire cross-sectional area of the openings 7 being smaller thanthe entire cross-sectional area of the openings 8.

By virtue of the arrangement of the openings 7 and 8 of the receivingcompartment 3 depicted in the drawing, the inlet openings 7 aresubjected to a greater hydrostatic pressure (H than the outlet ordischarge openings 8 I-I Due to contact of the molten cast iron with themagnesium, there result vapor bubbles which escape through the dischargeopenings 8. Consequently, there exists a through-flow of the molten castiron through the receiving compartment 3, so that there occurs a uniformreaction of the magnesium.

The vapor bubbles escaping through the openings 8 move through the melt2 towards the top and, in so doing, are intentionally taken up in partby the melt. The melt which is treated in this manner is again emptiedthrough the filling openings by tilting the treatment vessel 1. In orderto dampen the reaction of the pure magnesium located in the receivingcompartment 3, it is possible to additionally introduce into thiscompartment cold scrap iron or another cooling agent. Through thearrangement of one or a number of grid-like intermediate floors formedof refractory material in the vessel 1 (not shown), it is possible tostill further improve the yield of the additives. In order to obtain anoverpressure in the treatment vessel 1, it is possible to appropriatelyconstruct the cover member 6.

The mode of operation of the inventive method will now be explained inconjunction with the following examples:

Example 1 A cast iron melt of the following chemical composi tion:

Percent C 3.80 Si 1.80 Mn 0.57 P n 0.07 0.179

Percent S 0.002

Thus, the magnesium yield amounted to 66%. The structure of the casttest pieces after innoculation with 0.5% ferrosilicon consisted ofspherical graphite, that is to say, 96% Type VI according to VDGMerkblatt, P 441 and 4% Type V.

Example 2 A malleable cast iron melt of the following chemicalcomposition:

Percent C 2.88 Si a 1.65 Mn 0.27 P 0.08 S 0.163

had added thereto at a temperature of 1510 C., according to theinventive process, 0.28% pure magnesium in the form of bars, or ingots.The amount of iron to be treated amounted to 860 kg. The vaporization ofthe magnesium lasted 120 seconds. After emptying the treatment vesselinto a ladle, the following chemical composition was determined:

Percent S 0.002 Mg 0.056

Thus, the magnesium yield amounted to 63.5%.

Furthermore, it is known for the carburization of iron-carbon melts toadd carbon to the surface of the bath of a melt located in an electricinduction furnace. However, the degree of carburization with such atechnique is dependent to a large extent upon the agitation effect ofthe magnetic coils and the type of slag cover. With lower input power tothe electric furnace, carburization cannot be positively carried outand, moreover, the drawback exists that the carbon content on the orderof magnitude of 3.6 to 3.8% C, such as required for the production ofcast iron with spherical graphite, is considerably burned off in theelectric furnace. Furthermore, it is also known to undertakecarburization together with desulfurization in the ladle, whereby therequired bath movement, on the one hand, is produced by rotation orcentrifuging or, on the other hand, by air-or gas flushing.

These known techniques exhibit the drawback that the treatment timeslast up to 10 minutes and the carbon yield is low and subjected tocertain undesired fluctuations.

It has now been additionally found that is is possible to positivelycarburize and simultaneously desulfurize and, if desired, regulate theresidual magnesium content required for the spherical graphite formationof an ironcarbon melt in a simple manner, if during the performance ofthe inventive process before and/or during the introduction of magnesiuminto the iron-carbon melt, carbon is added to the surface of the bath.The carbon is added in the form of conventional carburizing agents,preferably in the form of coke grit or sand or graphite or carbonelectrodes.

The above method is especially suitable for the carburization of castiron, and indeed, specifically for the production of cast iron withspherical graphite.

During the production of cast iron with spherical graphite, it isnecessary to reduce the sulfur content of the melt delivered from theacidic adjusted cupola furnace and to increase the carbon content toapproximately 3.6 to 3.8% C.

As the treatment vessel there can advantageously be used a converter, assuch has previously been described in conjunction with FIGS. 1 and 2.

The carbon for carburization of the melt, after filling of the startingmelt, is added to the uncovered bath in the converter which is locatedin its horizontally extending position. After the subsequent rocking orpivoting of the converter into the vertically extending position, thevaporizing magnesium brings about a pronounced agitation of the bathwhich promotes carburization. Furthermore, the strongly reducingconditions, the basic slag, and the reduction of the sulfur content, actfavorably for carburization. Due to the cooperation of these conditions,it is possible to desulfurize a melt in a single working operationwithin! approximately 70 seconds to approximately 0.003% final sulfurcontent, and the carbon content can be increased by approximately 0.6%and the residual magnesium content can be regulated to the amountnecessary for cast iron with spherical graphite.

The formation of slag in the receiving compartment and in the openingsbetween this compartment and the treatment vessel can be prevented bythe addition of small amounts of fluxing agents, such as NaCl. In sodoing, the fluxing agent is added to the pure magnesium ingots, forinstance, in a ratio of 0.2 kg. NaCl/ 1000 kg. iron prior to treatmentin the receiving compartment.

With this technique, it is, for instance, possible, even with treatmenttemperatures of 1480 C., and a carbon equivalent of 4.2%, to carburizeby 0.7% a treated quantity of 900 kg. within 70 seconds with acarburization degree of 80%.

It should be apparent from the foregoing detailed description that theobjects set forth at the outset to the specification have beensuccessfully achieved.

Accordingly, what is claimed is:

1. In the introduction of metallic additives into a metal melt bycontacting the additive in solid form with the molten metal in asubmerged location in the melt, the improvement comprising providing areaction zone to contain the solid additive,

said zone having at least one inflow orifice and at least one outfloworifice,

the total cross-sectional area of said at least one inflow orifice beingsmaller than the total crosssectional area of said at least one outfloworifice, said at least one inflow orifice and said at least one outfloworifice being spaced from each other by a significant distance;

providing a body of molten metal in a melt-confining zone which isvented to the atmosphere;

providing in said reaction zone a quantity of an additive in solid form,

said additive being vaporizable at the temperature of the molten metalin said melt-confining zone and said quantity being adequate to effectan improving effect on said body of molten metal; and positioning saidreaction zone, with said reaction zone sealed save for said at least oneinflow orifice and said at least one outflow orifice, in a location atthe bottom of said melt-confining zone, with said at least one infloworifice adjacent the bottom of said meltconfining zone and said at leastone outflow orifice spaced thereabove,

said reaction zone being located a substantial distance below thesurface of said body of molten metal and there being a significantdifference between the hydrostatic pressure applied by said body ofmolten metal at said at least one outflow orifice and the hydrostaticpressure applied by said body of molten metal at said at least oneinflow orifice due to the space between said inflow and outflow orifice,

the step of positioning said reaction zone in a location at the bottomof said melt-confining zone causing molten metal to flow into saidreaction zone, via said at least one inflow orifice, into direct contactwith said additive, whereby said additive is caused to vaporize with thevapors so produced generating pres sure in said reaction zone at leastadequate to overcome the hydrostatic head of the molten metal and allowthe vapor to escape via said at least one outflow orifice into themolten metal, and such escape of the vapors allowing continued entry ofmolten metal into said reaction zone via said at least one infloworifice.

2. The improved method according to claim 1, wherein said molten metalis a cast iron melt having a substantial sulfur content, and

said additive is selected from the group consisting of magnesium alloys.

3. The improved method according to claim 2, wherein said additive ismagnesium.

4. The improved method according to claim 3, wherein a minor quantity ofa fluxing agent is provided in said reaction zone.

5. The improved method according to claim 4, wherein said fluxing agentis sodium chloride.

6. The improved method according to claim 1, wherein said reaction zonehas a plurality of outflow orifices;

and

said step of positioning said reaction zone is carried out to locate thesame adjacent one wall of said meltconfining zone, the transverse extentof said reaction zone being smaller than the transverse extent of saidmelt-confining zone.

7. The improved method according to claim 1, wherein cold metalcompatible with said molten metal is provided in said reaction zone todampen the reaction of said additive resulting when the molten metalentering via said inflow orifice contacts said additive.

8. The improved method according to claim 1, wherein said molten metalis a cast iron melt having a substantial sulfur content;

said additive is magnesium; and

the method further comprises adding carbon to said molten metal forcarburization thereof,

said carbon being present in the melt when the molten metal enters saidreaction zone, the vapors escaping from said reaction zone agitating themelt to promote carburization thereof.

9. In the treatment of a metal melt with a solid metallic additive, theimprovement comprising placing a quantity of the solid metallic additivein a chamber having at least one inflow orifice and at least one outfloworifice, the chamber being sealed save for said orifices,

the total cross-sectional area of said at least one inflow orifice beingsmaller than the total crosssectional area of said at least one outfloworifice, the locations of said at least one inflow orifice and said atleast one outflow orifice being spaced from each other by a significantdistance; and confining a body of the molten metal to be treated in aspace which surrounds said chamber in such fashion that said chamber islocated at the bottom of the body of molten metal and said at least oneoutflow orifice is spaced above said at least one inflow orifice, saidspace being vented to the atmosphere at a point above the surface of thebody of molten metal; said solid metallic additive vaporizing at thetemperature of said molten metal and the quantity of said additiveplaced in said chamber being adequate to provide an improving effect onthe quantity of said molten metal confined in said space; presence ofsaid body of molten metal in said space, and the fact that said bodyprovides a hydrostatic pressure at the location of said at least oneinflow orifice which is greater than the hydrostatic pressure at thelocation of said at least one outflow orifice, causing molten metal toflow into said chamber via said at least one inflow orifice and intocontact with said solid metallic additive,

contact of said molten metal with said additive causing said additive tovaporize, with the resulting vapors generating pressure in said chamberto oppose and thereby regulate the flow of said molten metal into saidchamber via said at least one inflow orifice and to cause said vapors toescape via said at least one outflow orifice into said body of moltenmetal.

10. The improvement according to claim 9, wherein said molten metal is acast iron melt and said additive is magnesium.

11. The improvement according to claim 9, wherein said space is definedby a vessel which is upright at the time of the flow of molten metalinto said chamber,

said chamber is of smaller horizontal extent than is said space and ispositioned off-center relative to said space, whereby a portion of saidbody of molten metal is beside said chamber, and

said at least one outflow orifice is directed generally upwardly andsaid at least one inflow orifice is directed generally laterally tocommunicate between the interior of said chamber and said portion ofsaid body of molten metal which is beside said chamber. 12. Theimprovement according to claim 11, wherein said molten metal is acast-iron melt having a substantial sulfur content; said additive ispure magnesium metal; and the method further comprises adding carbon tosaid molten metal for carburization thereof,

said carbon being present in said body of molten metal when molten metalflows into said chamber via said at least one inflow orifice, themagnesium vapor escaping from said chamber agitating said molten metalto promote carburization thereof.

References Cited UNITED STATES PATENTS 2,678,266 5/1954 Ziiferer 75-1302,754,201 7/ 1956 Zwicker 75-130 2,997,3 86 8 /1961 Feichtinger 75-933,295,960 1/1967 Parlee 75-93 10 Robertson 75-130 X Fishell 75-130 B XKlingbeil 75-130 B X Grandpierre 75-130 B Wallace 75-123 Schelleng75-130 X Kopke 75-130 B X OTHER REFERENCES 10 K. J. Wastschenko and L.Sofroni, Magnesiumbehandeltes Gusseisen, Leipzig, Germany, vebD'eutscher Verlag fiir Grundstotfindustrie, 1960, p. 141-144.

L. DEWAYNE RUTLEDGE, Primary Examiner 15 I. E. LEGRU, Assistant ExaminerUS. Cl. X.R.

